1. Field of the Invention
This invention relates to a hand-held haptic control system with tactile force feedback that acquires dynamic cardiac mechanical data as to generate multidimensional tactile simulations of the intra-cardiac environment in real time via a hand held Cardiovascular Haptic Handle (CHH) providing physiologic information in form of a tactual representation in real time. The CHH system eliminates the effects of a catheter's dampening properties, the attenuation effects of intervening tissues and the affect of the operator's gross motions on an inserted catheter's ability to provide the operator with a tactual representation of cardiac tissue motion and the effects of catheter—tissue contact. Though the system can function in conjunction with visual displays, it can provide mechanical and anatomical information with a haptic representation and replace the need for a visual display.
2. Description of Prior Art
Medical catheters and sheaths are generally tubular shaped and of a sufficiently small diameter to be inserted into a patient's body through a small incision, puncture or a natural opening. Such catheters can be used to deploy inner catheters, cardiac leads, electrodes, deliver contrast (e.g. radiopaque dye) or ablative energy in form of electromagnetic energy (e.g. current, radiofrequency energy, light) and are flexible as described by Brock et al in U.S. patent application Ser. No. 12/023,685. One example is lead extraction systems that implement an excimer laser. Unfortunately, as conventionally designed catheters course through a patient's tissues and vasculature the operator looses his or her ability to appreciate the forces restricting catheter motion secondary to attenuation and frictional effects and due to the compliant nature of the inserted catheters.
Catheters for performing coronary/peripheral angiography and vascular interventions are well understood by those experienced in the art. More recently, catheters have been designed for engaging the coronary sinus and positioning pacing leads about the left ventricle for cardiac resynchronization therapy which is often difficult and time consuming requiring large amounts of radiation exposure. These catheters can also dissect vessels and intracardiac structures leading to cardiovascular collapse. Unfortunately, the operator can not appreciate the dynamic characteristics of contacted tissue or the forces along the distal portion of these catheters and mainly relies on radiographic images during catheter manipulation (e.g. fluoroscopy). These images are two dimensional and necessitate exposure to radiation. Tactile feedback systems incorporated into the design of these catheters would reduce complication rates, expedite procedures and minimize radiation exposure to the operator and patient alike and most importantly, provide insights into cardiac tissue mechanics.
Electrograms have been demonstrated to be poor predictors of electrode-tissue contact for ablation procedures (see Ikeda A. et al. Electrogram Parameters (Injury current, amplitude, dV/dt) and Impedance are poor predictors of electrode-tissue contact force (see Electrode-Tissue Contact Force for Radiofrequency Ablation. Heart Rhythm Society, May 2008, Abstract 4570, P05-41).
The phasic nature of the contracting heart and respirations affects lesion characteristics from ablative energy because of intermittent contact and variations in applied force at the electrode-tissue interface (Shah D C et al. Area under the real-time contact force curve (force-time integral) predicts radiofrequency lesion size in an in vitro contractile model. J Cardiovac Electrophysiol, 2010, pp 1-6). Real-time tactile force-feedback via the Haptic Handle will ensure safe and effective delivery of therapy without a need for the operator to look away from the visual/fluoroscopic image of the heart and obviates a need to look at a separate force graphic display during critical time frames. The CHH will complement technologies that provide force information (available e.g. from Endosense Tacticath of Geneva Switzerland, Hansen Medical of Mountainview, Calif.) and improve outcome with minimal additional expense, obviate the need for expensive navigational systems and reduce fluoroscopic exposure. It will also enable the operator to more deeply sedate patients during their procedures as verbal feedback of discomfort during delivery of ablation energy will not be necessary.
A variety of devices can be used as a haptic display including but not limited to programmable keyboards, augmented mice, trackballs, joysticks, multi-dimensional point and probe-based interactions, exoskeletons, vibro-tactor arrays, gloves, magnetic levitation, and isometric devices (Burdea, G C. Force and Touch Feedback for Virtual Reality. New York: Wiley Interscience, 1996). These systems are used for virtual simulations or for evaluation of non-moving, static structures. There remains a need for haptic representation of moving biological tissue.
Mottola et al (U.S. Pat. No. 6,059,759) describes an infusion catheter system with an occluding wire that generates vibrations when the wire protrudes along a ridge notifying the operator that the wire extends beyond the confines of the inserted catheter. This does not provide the operator with information about the mechanics of cardiac motion/deformation or the effect of the catheter on cardiac mechanics.
Wallace D, et al has developed a robotic catheter manipulator that includes at least one force sensor for measuring the force applied to the working catheter by a ditherer during operation (U.S. patent applications publications nos. 20070233044, 20070197939). Force measurements are estimated and displayed to the physician via a monitor or display. In Wallace's application, an alarm signal can notify the operator that too high a force is applied via an audio, video or haptic signal, though there is no tactile appreciation or simulation of tissue mechanics/motion present at the distal portion of the catheter. Such a design is found in ablation catheters manufactured by Hansen Medical Inc., Mountainview, Calif.
No current technology provides the operator with a dynamic mechanical simulation of the heart, surrounding vasculature or the effect of an inserted instrument on cardiovascular tissue deformation and motion. The addition of tactile force feedback to commonly used catheter manipulators will provide an operator with a unique ability to sense the physical action of an inserted catheter on a rapidly moving biological structure while controlling fine motion of the catheter's distal aspect and acquiring physiologically significant data about cardiac function.
References—to be Listed Separately in an IDS.